1. Field of the Invention
The present invention relates to parachutes, and more particularly to an improved parachute leading edge structure and shape.
2. Description of the Prior Art
Conventional canopies are well known in the art. These canopies usually have a top and bottom surface. The canopy will have a leading and trailing edge. The bottom and top surface will usually be connected at their respective trailing edges. These canopies also include a plurality of rib members extending from the trailing to the leading edge. The rib members in conjunction with the top and bottom surface will define a plurality of air chambers. The respective leading edges of the top and bottom surface and the rib members will have leading edge reinforcements. In conventional canopies the rib leading edge reinforcement terminates at the top surface leading edge reinforcement.
The air movement past the top surface of the canopy must travel faster than air movement past the bottom surface for the canopy to lift. The difference in speed leads to a decreased pressure over the top of the canopy, a pressure which is equivalent to a suction force that lifts the canopy. The greater the difference in air speeds surrounding the top and bottom surfaces, the greater the lift that is produced, provided the canopy shape is not so extreme that turbulence results.
Wing-type parachutes are known to be inherently unstable. The lift they produces equals the suspended weight therefrom. The lift is a function of air speed and the angle of attack. The angle of attack is determined by where the center of pressure is located and the center of pressure is determined by the angle of attack. This leads to an inherently unstable parachute. When the angle of attack is decreased, the air speed increased and the center of pressure moves. This causes the angle of attack to be further reduced, which in turn causes the center of pressure to move aft and the air speed to increase. This cycle continues until either the drag increases enough to stabilize the system, or the canopy goes beyond the zero lift line and collapses.
By having its rib leading edge terminate at the top surface leading edge reinforcement, turbulence occurs. As mentioned above, this turbulence reduces the canopy lift. Therefore, there exists a need for an improved canopy leading edge structure that will reduce turbulence in order to increase the canopy lift. In addition, conventional canopies are known to open very quickly. By opening quickly, the canopy experiences deployment shock loads. Therefore, there exists a need for an improved canopy leading edge structure that will cause the canopy to open slower than conventional canopies and, thus, reduce deployment shock loads.